Late last week a new jailbreak method was released for iOS 4 and iPhone OS 3.x based devices such as the iPhone, iPod, and iPad. Jailbreaking these devices is nothing new. It's been done for years to allow these devises to run applications not approved by Apple, and also as a means to unlock iPhones for use on other carriers. What is different in this new method is that all that it takes to jailbreak the device is to visit a specific website using the built-in Web browser. Previously users had to connect the device to a computer and use software for Windows or Mac to complete the process.

At jailbreakme.com, all it takes to complete the jailbreak is to slide the arrow to the right and wait for the process to complete. To perform the jailbreak the process takes advantage of two vulnerabilities; one in how Safari parses PDF files, and one in the kernel of iOS/iPhoneOS. VUPEN has more information about these vulnerabilities in their advisory.

Apple is reportedly looking into the vulnerability issues, but until they have issued a patch, all users of iPhones, iPads, or iPods are at risk, because there is nothing that prevents a malicious attacker from using these vulnerabilities to automatically install malware onto the device. Reports around the Web are claiming that there isn't much a user can do to prevent this type of attack unless you've already jailbroken, as there is an add-on, via Cydia, that will warn you for every PDF you open. However, this is not entirely true.

While it is true that Safari and other Web browsers on iOS/iPhoneOS automatically render and display a PDF page, and therefore will load the exploit automatically, some third-party browsers have customizable filters that can block the attack and prevent your device from compromise. Two examples are Atomic Web Browser and iCabMobile, both of which work on iPhone, iPod Touch, and iPad.

Here is how you enable and tweak the application filters to prevent PDFs from being downloaded in the browser.

If you havenxxx8217;t already given it a go, cracking your iPhone by using the JailbreakMe.com website is the easiest it has ever been to let the leash off your iPhone, however, as handy though the method is, it has highlighted a potentially problematic vulnerability within Mobile Safari.

Herexxx8217;s the issue. JailbreakMe.com hides its code inside a PDF document with a dodgy font, which when activated allows the implanted code to run the jailbreak program with little to no input from the user aside from the xxx8217;slide to jailbreakxxx8217; instruction. According to several sources, including Gizmodo, this exploit could also be used by less friendly sources to take control of your device, wipe its memory, install new programs or pretty much anything else they fancy.